This invention relates to multilayer composites having at least one metal layer and at least one layer of thermoplastic organic polymer and to articles formed therefrom.
Metallized plastic articles prepared by applying a metal to a plastic material by vacuum deposition, electrolytic or electroless deposition, foil lamination or similar metallizing techniques are well known. Such articles are widely employed for decorative purposes, particularly the metallized films which are quite flexible and can be shaped to some extent to conform to various contours.
Unfortunately, the degree to which such conventional metallized films or sheets or other articles can be shaped without rupture and/or separation of the metal from the polymer is generally limited to those shaping procedures involving localized dimensional changes of less than 25 percent in one direction and less than 20 percent (based on area of the film) if the dimensional changes are in two directions. The visual effect of stretching the metallized polymer beyond this limit is a noticeable loss of specular reflectance at the points of excessive elongation. The resulting article has a marred appearance and diminished utility in decorative, electrical and packaging applications.
As a result of the loss of barrier properties caused by actually stretching the metallized polymer beyond the 20 percent limit, the use of such metallized polymers in many packaging applications is severely reduced, particularly where high barrier to vapor transmission is critical. Likewise, the corresponding loss of electrical conductivity reduces the suitable electrical applications to those involving minimal dimensional change.
In addition, the aforementioned limitation on the amount of dimensional change of the metallized polymers significantly hinders their use in the manufacture of reflective parts (often called bright work) for automobiles and other vehicles of transportation as well as for household appliances. Such reflective parts often require biaxial extension such that the stretched article occupies an area more than 50 percent greater than the area of the article prior to stretching.
In view of the aforementioned needs for novel highly extendable, multilayer metal/polymer composites and the deficiencies of existing metallized polymer articles in this regard, it would be highly desirable to provide a multilayer, metal/organic polymer composite that exhibits excellent specular reflectance, electroconductivity and barrier to vapor transmission after substantial dimensional change.